CETROS DE SALUD DEL ÁREA 17

Geological layer is classified into 7 types based on soil sample observation and results of the laboratory test as shown in Table 4-1.

Geological / Geomorphic data and boring with soil test data (carried out by this project) [see Chapter 1 and Chapter 2]

Geological classification at every boring point in each 1.5m (SPT) depth

[see Section 4.2.2]

Calculation of AVS30 using boring data (carried out by this project) by the relationship between Vs and N-value

[see Section 4.2.4]

Setup of correlated equation between S-wave velocity (Vs) by PS logging and N-value by SPT in each geological layer

[see Section 4.2.3]

Setup of thickness of geological layer (Holocene;

Modhupur Clay, Dupi Tila, Tipam, Bokabil) in each 250 m grid including boring points

[see Section 4.2.6]

Setup of relationship between thickness of Holocene soil and AVS 30 from boring data (carried out by this project)

[see Section 4.2.5]

Establishment of AVS 30 at each grid for estimation of amplification at subsurface ground

[see Section 4.2.7]

Point Base Analysis

Analysis for Area-wide

Table 4-1 Tabulation of Geological Classification Geological Classification Dhaka Chittagong Sylhet Recent Fill

(F)

● ● ●

Holocene

Clayey Soil

(H-C)

● ● ●

Sandy Soil

(H-S)

● ● ●

Pleistocene Modhupur Clay

(MC)

●

Pliocene Dupi Tila

(DT)

● ● ●

Each geological classification has characteristics of N-value as shown in Figure 4-3, and the characteristics reflects S-wave velocity features (refer to Section 4.2.3)

5.2

Figure 4-3 N-value Characteristics of each Geological Classification

18.0 N=-0.7Dep + 11.2

53.3 N=-1.4Dep + 20.0

-36.0 61.5

Figure 4-3 (cont.) N-value Characteristics of each Geological Classification

103.7 -36.0

-34.5 -33.0 -31.5 -30.0 -28.5 -27.0 -25.5 -24.0 -22.5 -21.0 -19.5 -18.0 -16.5 -15.0 -13.5 -12.0 -10.5 -9.0 -7.5 -6.0 -4.5 -3.0 -1.5 0.0

0 20 40 60 80 100 120 140 160 180 200

Depth (GL -m)

N-value

Bk

DHK CTG SYL Average

Figure 4-3 (cont.) N-value Characteristics of each Geological Classification

All borings carried out by this project are expressed by the geological classification at every 1.5 m in depth where SPT were conducted as shown in Figure 4-5 (Dhaka), Figure 4-8 (Chittagong) and Figure 4-11 (Sylhet).

At PS logging points, these geological classification are utilized as soil modeling of 1D response analysis (refer to Section 2.2 in Report of “Seismic Hazard Map”).

(1) Dhaka

At subsurface ground in central part of the study area from north to south direction and its surroundings distributes Modhupur Clay and Fill / Holocene soil, respectively, as shown in Figure 4-4.

Fill is located in old wetland / water body and basically made by very loose sand without adequate compaction work, thus it is evaluated that this area is liquefiable induced by a strong seismic motion. Holocene soil consists of loose sandy soil and soft clayey soil with quite complicated distribution, and it is difficult to make a detailed soil modeling due to no horizontal-stratification.

*Red-tinged color shows Modhupur Clay.

[The geomorphic map was edited by GSB]

Figure 4-4 Geomorphic Map with the Investigation Points in Dhaka

Geological strata consist of, from topsoil to downward, Fill, Holocene soil (clayey soil and sandy soil), Modhupur Clay and Dupi Tila as shown in Figure 4-5.

Upper Depth Dhk_01 Dhk_02 Dhk_03 Dhk_04 Dhk_05 Dhk_06 Dhk_07 Dhk_08 Dhk_09 Dhk_10 Dhk_11 Dhk_12 Dhk_13 Dhk_14 Dhk_15 Dhk_16 Dhk_17 Dhk_18 Dhk_19 Dhk_20 Dhk_21 Dhk_22 Dhk_23 Dhk_24 Dhk_25 Dhk_26 Dhk_27 Dhk_28 Dhk_29 Dhk_30 Dhk_31 Dhk_32 Dhk_33 Dhk_34 Dhk_35 Dhk_36 Dhk_37 Dhk_38 1.5 F MC F F F H-CMC F F F H-S F F H-C H-CH-SH-C H-CH-SH-C F MCH-C H-CMCH-C F H-C F H-S F H-C H-C H-C F H-C F MC 3.0 F MCH-C H-C F H-CMC H-S MC F H-SMC MCH-C H-C H-C H-C H-C H-CMC MC MCH-C H-CMCH-C H-C H-C H-CH-S F H-C H-CH-S F H-C H-CMC 4.5 MC MCH-C H-CMCH-CMCH-CMCH-CH-SMC MCH-C H-C H-C H-C H-C H-CMC MC MCH-C H-CMC MCH-C H-C H-CH-SH-C H-C H-C H-C H-C H-C H-CMC 6.0 MC MCH-C H-CMCH-CMC H-S MCH-CH-SMC MCH-CMCH-C H-C H-C H-CMC MC MC MCH-CMC MCH-C H-C H-C H-CMCH-C H-C H-C H-C H-C H-CMC 7.5 MC MCH-C H-CMCH-CMCH-CMCH-CH-SMC MCH-CMC MCH-C H-C H-CMC MC MC MCH-CMC MCH-CMCH-CH-SMCH-C H-CMC MCH-CMC MC 9.0 MC MCH-C H-CMCH-CMCH-CMCH-CH-SMC MC H-S MC MC H-SH-C H-CMC MC MC MCH-CMC MC H-S MCH-CH-SMCH-C H-CMC MCH-CMC MC 10.5 MC MCH-CH-SMCH-CMC H-S MCH-CH-SMC MC H-S MC MC MCH-C H-CMC MC MC MCH-CMC MC H-S MC H-S H-S MC H-SH-CMC MCH-CMC MC 12.0 MC MC MC H-S MCH-CMC H-S MC H-S H-S MC MC H-S MCDTMCH-C H-CMC MC MC MCH-CMC MC H-S MC H-S H-SDTH-SH-CMC MCH-CMC MC 13.5 MC MC MCH-CMCH-CMC H-S MC H-S H-S MCDTH-SMCDTMCH-C H-CMC MC MC MCH-CMC MCDTMCH-C H-CDTH-C H-CMC MCH-CMC MC 15.0 MC MC MC MC MCH-CMC H-S MC H-S H-SDT DTMC MCDT DTH-C H-CMCDTMC MCH-CMC MCDT DTH-SH-CDTMCH-CMC MCDTMC MC 16.5 MC MC MCDTMCH-CMC H-S MCH-CH-SDT DTMC MCDT DTH-C H-CMCDT DT DTH-CMC MCDT DTH-SH-CDTMCH-CMC MCDTMC MC 18.0 MC MC MCDTMC H-S MC H-S MCH-CH-SDT DTMC MCDT DTH-S H-SMCDT DT DTH-CMC MCDT DTH-SH-CDTMCH-CMCDT DTMCDT 19.5 MC MC MCDTMC H-S MC H-S MCH-CH-SDT DTMC MCDT DTH-SH-CMCDT DT DTH-CMC MCDT DTH-SH-CDTMCH-CMCDT DTMCDT 21.0 MC MC MCDTMC MC MC H-S MC MC H-SDT DT DTMCDT DTH-SH-CMCDT DT DT DTMC MCDT DTH-SH-CDTMCH-CMCDT DTMCDT 22.5 MC MCDT DTMC MC MC H-S MC MC H-SDT DT DTMCDT DTH-SH-CMCDT DT DT DTMC MCDT DTH-S H-SDTMCH-CMCDT DT DT DT 24.0 MC MCDT DTMC MC MC H-S MC MC H-SDT DT DTMCDT DTH-SH-CMCDT DT DT DTMC MCDT DTH-SH-CDT DTMC MCDT DT DT DT 25.5 MC MCDT DTMCDTMC H-S MC MC H-SDT DT DTMCDT DT DTH-CMCDT DT DT DTMC MCDT DTH-S H-SDT DTMC MCDT DT DT DT 27.0 MC MCDT DT DT DTMC H-S MC MC H-SDT DT DTMCDT DT DTH-CMCDT DT DT DTMCDT DT DTH-S H-SDT DT DTMCDT DT DT DT 28.5 MC MCDT DT DT DTMC H-S MC MC H-SDT DT DTMCDT DT DTH-CDT DT DT DT DTMCDT DT DTH-S H-SDT DT DTMCDT DT DT DT 30.0 MCDT DT DT DT DTMC H-SDTMC DT DT DTMCDT DT DTH-CDT DT DT DT DTMCDT DT DTH-S H-SDT DT DTMCDT DT DT DT 31.5 DT DT DT DTMC H-SDTMC

33.0 DT DT DTMC H-SDT DT

34.5 H-SDT DT

Figure 4-5 Geological Classification at the Borings in Dhaka

The strata generally consist of 3 layers, which are Holocene soil including Fill, Modhupur Clay and Dupi Tila, as shown in Figure 4-6. Thickness of Modhupur Clay gradually becomes thin or is disappeared towards boundary of the study area. Dupi Tila distributes whole study area, and surface of Dupi Tila in the central part and its surroundings are encountered in shallow portion (shallower than 20 m in depth from ground surface) and in the deeper portion (deeper than 30 m in depth beside the study area boundary).

(2) Chittagong

There are hill area and plane area in Chittagong study area. Dupi Tila, Tipam and Bokabil outcrop in the hill area, and Fill / Holocene soil distributes in the plane area as shown in Figure 4-7.

Fill is located in old wetland / water body and basically made by very loose sand without adequate compaction, thus it is evaluated that this area is liquefiable induced by a strong seismic motion. Holocene soil consists of loose sandy soil and soft clayey soil with quite complicated distribution, and it is difficult to make a detailed soil modeling due to no horizontal-stratification.

[The geomorphic map was edited by GSB]

Figure 4-7 Geomorphic Map with the Investigation Points in Chittagong

Geological strata consist of, from topsoil to downward, Fill, Holocene soil (clayey soil and sandy soil), and Dupi Tila / Tipam / Bokabil, which are seismic engineering baserock, as shown in Figure 4-8.

Upper Depth Ctg_01 Ctg_02 Ctg_03 Ctg_04 Ctg_05 Ctg_06 Ctg_07 Ctg_08 Ctg_09 Ctg_10 Ctg_11 Ctg_12 Ctg_13 Ctg_14 Ctg_15 Ctg_16 Ctg_17 Ctg_18 Ctg_19 Ctg_20 Ctg_21 Ctg_22 Ctg_23 Ctg_24 Ctg_25 Ctg_26 Ctg_27 Ctg_28 Ctg_29 Ctg_30 Ctg_31 Ctg_32 Ctg_33 Ctg_34 Ctg_35 Ctg_36 Ctg_37 Ctg_38 1.5 F F F H-S F F F H-CH-SH-C H-C H-C H-C H-C H-CH-SH-C F H-C F F H-C F H-C H-C H-CH-S H-SH-C H-CH-SH-CH-S H-SH-C H-CH-SH-C

3.0 H-C H-C H-C H-C H-C F H-C H-CH-SH-C H-C H-C H-C H-C H-CH-SH-C H-C H-C H-CH-SH-C H-CH-S H-SH-CH-S H-SH-C H-CH-SH-C H-CH-SH-C H-CH-SH-C

4.5 H-C H-C H-C H-C H-C H-CH-S H-SH-C H-C H-C H-C H-C H-C H-CH-SH-C H-C H-C H-CH-SH-C H-C H-CH-SH-CH-S H-SH-C H-C H-C H-C H-C H-C H-C H-CH-SH-C

6.0 H-C H-C H-C H-C H-C H-CH-S H-SH-C H-C H-C H-C H-C H-C H-C H-C H-C H-C H-C H-CH-S H-SH-C H-CH-S H-S H-S H-SH-C H-C H-C H-C H-C H-C H-C H-CDTH-C

7.5 H-C H-C H-C H-C H-C H-CH-S H-S H-SH-CH-SH-C H-C H-C H-C H-C H-CH-SH-C H-CH-S H-SH-C H-CH-S H-S H-SBKH-C H-C H-C H-C H-C H-C H-C H-CDTH-C

9.0 H-C H-C H-C H-CH-SH-C H-C H-C H-CH-S H-SH-C H-C H-C H-C H-C H-CH-SH-C H-CH-S H-S H-S H-SH-C H-CH-SBKH-C H-C H-C H-C H-CH-SH-C H-CDTH-C

10.5 H-C H-C H-C H-C H-C H-C H-CH-S H-S H-S H-SH-C H-C H-CH-SH-C H-C H-C H-C H-CH-S H-S H-S H-SH-C H-CH-SBKH-C H-C H-C H-C H-C H-C H-CDT DTH-C

12.0 H-C H-C H-C H-C H-C H-CTpH-S H-S H-S H-SH-C H-C H-CH-SH-C H-CH-S H-SH-C H-CH-S H-S H-S H-S H-S H-SBK BKH-CH-S H-SH-C H-C H-CDT DTH-C

13.5 H-C H-C H-C H-C H-C H-CTpH-S H-S H-S H-SH-C H-C H-C H-C H-C H-CTpH-SH-CH-S H-SH-C H-CH-S H-S H-SBK BK BKH-SH-CH-S H-SH-CDT DTH-C

15.0 H-C H-C H-CH-SBkH-CTpH-CH-SH-CH-S H-SH-CH-SH-C H-C H-CTpH-C H-CH-S H-S H-S H-S H-S H-S H-SBK BK BKH-CH-S H-STpH-CDT DTH-C

16.5 H-C H-C H-CH-SBkH-CTpH-CH-SH-CH-S H-SH-CH-S H-S H-STp TpH-S H-STpH-CH-S H-S H-S H-SH-C BK BKH-S H-S H-STpH-CDT DTH-C

18.0 H-C H-C H-CH-SBkH-STpH-C H-CTpH-CH-S H-S H-SH-CH-STp TpH-S H-STpH-CH-S H-S H-S H-SH-C BK BKH-S H-SH-CTpH-CDT DTH-C

19.5 H-C H-CH-S H-SBkH-CTpH-S H-STpH-C H-CH-S H-SH-CDT Tp TpH-CH-STpH-C H-CH-SH-CH-SH-C BK BKH-S H-S H-STpH-CDT DTH-S 21.0 H-C H-CTpH-CBkH-STpH-S H-STpH-C H-C H-CH-SH-CDT Tp TpH-STp TpH-C H-C H-C H-CH-SH-C BK BKH-S H-S H-STpH-CDT DT DT 22.5 H-C H-CTpH-SBk Bk TpH-CH-STpH-C H-C H-C H-C H-CDT Tp TpH-STp TpH-C H-C H-C H-C H-C H-C BK BKH-S H-STp TpH-SDT DT DT 24.0 H-SH-CTpH-SBk Bk TpH-CH-STpH-C H-C H-C H-C H-CDT Tp TpH-STp TpH-C H-C H-C H-C H-C H-C BK BKH-S H-STp TpH-SDT DT DT 25.5 H-SH-CTpH-CBk Bk TpH-CTp TpH-C H-C H-C H-C H-CDT Tp TpH-CTp TpH-C H-CH-SH-C H-C H-C BK BKH-S H-STp TpH-SDT DT DT 27.0 H-C H-CTpH-CBk Bk TpH-STp TpH-C H-C H-C H-CH-SDT Tp TpH-CTp TpH-C H-CH-SH-C H-C H-C BK BKH-S H-STp TpH-SDT DT DT 28.5 H-C H-CTpH-CBk Bk TpH-STp TpH-C H-C H-C H-CH-SDT Tp TpH-CTp TpH-C H-CH-SH-C H-C H-C BK BKH-S H-STp TpH-SDT DT DT 30.0 H-C H-CTpH-CBk Bk TpH-STp Tp H-C H-C H-CH-SDT Tp TpH-CTp TpH-C H-CH-S H-SH-CH-S BK BKH-S Tp TpH-SDT DT DT

31.5 H-S H-C Tp Tp H-S H-C BK

33.0 H-S H-C H-S H-C

34.5 H-S H-S H-C

36.0 H-S

Figure 4-8 Geological Classification at the Borings in Chittagong

The strata generally consist of 2 layers, which are Holocene soil and Dupi Tila / Tipam / Bokabil, as shown in Figure 4-9. Thickness of Holocene soil becomes thick from hill area to sea side (westward) and inland side (eastward), and is more than 30 m in wide area.

(3) Sylhet

There are hill area and plane area in Sylhet study area. Dupi Tila outcrops in the hill area and Fill / Holocene soil distributes in the plane area as shown in Figure 4-10.

Fill is located in old wetland / water body and basically made by very loose sand without adequate compaction, thus it is evaluated that this area is liquefiable induced by a strong seismic motion. Holocene soil consists of loose sandy soil and soft clayey soil with quite complicated distribution, and it is difficult to make a detailed soil modeling due to no horizontal-stratification.

[The geomorphic map was edited by GSB]

Figure 4-10 Geomorphic Map with the Investigation Points in Sylhet

Geological strata consist of, from topsoil to downward, Fill, Holocene soil (clayey soil and sandy soil), and Dupi Tila, which are seismic engineering baserock, as shown in Figure 4-11.

Upper Depth Syl_01 Syl_02 Syl_03 Syl_04 Syl_05 Syl_06 Syl_07 Syl_08 Syl_09 Syl_10 Syl_11 Syl_12 Syl_13 Syl_14 Syl_15 Syl_16 Syl_17 Syl_18 Syl_19 Syl_20 Syl_21 Syl_22 Syl_23 Syl_24 Syl_25 Syl_26 Syl_27 Syl_28 Syl_29 Syl_30 Syl_31 Syl_32 Syl_33 Syl_34 Syl_35 Syl_36 Syl_37 Syl_38 1.5 H-C H-C H-C H-C H-C F H-SH-C H-C H-C H-C H-C H-C H-CH-S F H-CDTH-S H-SH-C H-C H-C H-C H-C H-C H-CH-S F H-C H-C H-C H-C H-C H-CH-S H-S H-S 3.0 H-C H-C H-CH-SH-C F H-C H-C H-C H-C H-C H-C H-C H-C H-CH-SH-CDTH-SDTH-S H-SH-C H-C H-C H-C H-CH-S H-SH-C H-C H-C H-C H-C H-CH-S H-S H-S 4.5 H-C H-C H-C H-C H-C H-CH-SH-C H-C H-C H-C H-CH-S H-SH-CH-SH-CDTH-SDTH-CH-SH-C H-C H-C H-C H-C H-CDTH-C H-C H-C H-C H-C H-CH-SH-CH-S 6.0 H-SH-CH-SH-CDTH-CDT DTH-CH-SH-C H-CH-S H-SH-CH-S H-SDTH-SDTH-CH-SH-CH-S H-SH-C H-C H-CDTH-C H-C H-C H-C H-C H-CH-SH-C H-C

7.5 H-C H-C H-CH-SDTH-SDT DTH-CH-SH-CH-S H-SH-C H-CH-S H-SDT DT DTH-CH-SH-C H-CDTH-C H-CH-SDTH-C H-C H-C H-C H-C H-CH-SH-CH-S 9.0 H-C H-C H-CH-SDTH-SDT DTH-C H-C H-CH-SH-CH-S H-S H-S H-SDT DT DTH-CH-S H-S H-SDTH-C H-C H-CDTH-C H-C H-C H-C H-CH-S H-SH-CH-S 10.5 DTH-C H-C H-CDT DT DT DTH-C H-C H-C H-CH-SH-CH-SH-CH-SDT DT DT DTH-S H-SH-CDTH-C H-CDT DTH-C H-CH-SH-C H-CH-S H-SH-C H-C

12.0 DTH-C H-C H-CDT DT DT DTH-C H-C H-C H-C H-C H-CH-SDTH-SDT DT DT DTH-SDTH-CDTH-C H-CDT DTH-C H-CH-SH-C H-CH-S H-SH-C H-C

13.5 DTH-C H-C H-CDT DT DT DTH-C H-C H-C H-C H-CH-SDT DTH-SDT DT DT DTH-SDTH-CDTH-C H-CDT DTH-C H-CH-S H-SH-C H-CH-SDTH-C

15.0 DTH-CH-SDT DT DT DT DTH-C H-C H-CDT DTH-CDT DTH-SDT DT DT DTH-SDTH-CDTH-C H-CDT DTH-C H-CH-S H-SH-C H-CH-SDTH-C

16.5 DTH-CDT DT DT DT DT DTH-C H-CDT DT DTH-SDT DTH-CDT DT DT DTH-CDTH-CDTH-CDT DT DTH-C H-CH-SH-CH-SH-CH-SDTH-C

18.0 DTH-SDT DT DT DT DT DT DTH-CDT DT DTH-SDT DTH-CDT DT DT DTH-CDTH-CDTH-CDT DT DTH-C H-C H-C H-CH-SH-CH-SDT DT 19.5 DTH-CDT DT DT DT DT DT DTH-CDT DT DTH-SDT DT DT DTH-CDTH-CDTH-CDT DT DTH-C H-C H-C H-C H-CH-S H-SDT DT 21.0 DTH-CDT DT DT DT DT DT DTH-CDT DT DTH-SDT DT DT DT DT DTH-SDT DT DT DT DT DTH-SDTH-C H-C H-CH-SDT DT 22.5 DT DT DT DT DT DT DT DT DT DT DT DT DTH-SDT DT DT DT DTH-SDT DT DT DT DTH-CDTH-C H-C H-C H-CDT DT 24.0 DT DT DT DT DT DT DT DT DT DT DT DT H-SDT DT DT DT DTH-CDT DT DT DT DTH-CDTH-C H-C H-C H-CDT DT 25.5 DT DT DT DT DT DT DT DT DT DT DT DT H-SDT DT DT DT DTH-CDT DT DT DT DTH-CDTH-CH-SH-C H-CDT DT 27.0 DT DT DT DT DT DT DT DT DT DT DT DT DT DT DT DT DTH-CDT DT DT DT DTH-CDTH-CH-SH-CDT DT DT 28.5 DT DT DT DT DT DT DT DT DT DT DT DT DT DT DT DTH-SDT DT DT DTH-CDTH-S H-SH-CDT DT DT 30.0 DT DT DT DT DT DT DT DT DT DT DT DT DT DT H-SDT DT DT DTH-CDTH-S H-SH-CDT DT DT

31.5 DT

Figure 4-11 Geological Classification at the Borings in Sylhet

The strata generally consist of 2 layers, which are Holocene soil and Dupi Tila as shown in Figure 4-12. Thickness of Holocene soil irregularly becomes thick from hill area to south / south-east / south-west side.

Figure 4-12 Schematic Geological Cross Section in Sylhet